The spinal accessory nerve in childhood hemiplegia

Fifteen of 17 children with hemiplegia were found to have weakness of the trapezius muscle but a normally functioning sternocleidomastoid muscle. Very few other cranial nerve-mediated deficits were found. The difference between the two muscles, both supplied by the spinal accessory nerve, may depend on a phylogenetic basis, with the former behaving like an appendicular muscle and the latter like an axial muscle.